AUTONOMIC NERVOUS SYSTEM Automatic response-the body’s way of
unconsciously and automatically making decisions and carrying them out for you.
The autonomic nervous system-is part of the peripheral nervous system that supplies motor activity to the visceral effector organs, glands, smooth muscles within the organs and the heart.
DIVISIONS OF THE ANS The two divisions of the ANS are:
sympatheticParasympathetic
Dual Innervation a single organ receives nerve fibers from both divisions of the ANS
Sympathetic nervous system- is activated during periods of stress or times when a person feels threatened.
Called the “fight or flight” response.
SYMPATHETIC NERVOUS SYSTEM Causes you to either confront (fight) or remove yourself from the threatening
situation (flight).
Sympathetic nervous system is activated during periods of stress, normally short-lived periods.
SYMPATHETIC RESPONSE Heart rate increases Bronchial tubes dilate(increase airflow) Iris of the eye dilates (pupils enlarge) Blood vessels constrict Sweat glands stimulated Inhibited intestinal mobility Adrenal medulla stimulates secretion of
epinephrine and norepinephrine Salivary glands stimulate thick
secretions
PARASYMPATHETIC NERVOUS SYSTEM Parasympathetic nervous system-most
active during quiet, non-stressful conditions.
Has a calming effect on the body.
Plays an important role in the regulation of digestion and reproductive function.
Referred to as “feed and breed” or resting and digesting.
PARASYMPATHETIC NERVOUS SYSTEM The parasympathetic system is
activated in situations that are perceived hopeless and where “fight or flight” seems futile.
Symptoms are the opposite of sympathetic nervous system
Body’s reaction to a more restful situation.
Ex. Nice spring day, sitting under a tree.
PARASYMPATHETIC RESPONSE Decreased heart rate Bronchial tubes constrict Pupils Constrict Salivary glands are stimulated with a
watery secretion Increased motility and secretion of the
intestine
PARASYMPATHETIC RESPONSE Stimulus that can effect the
parasympathetic nervous system may be stimulation of the vagus nerve, diagnostic testing that may stimulate a parasympathetic response. Ex. Colonoscopy.
A massive parasympathetic response may result in uncontrolled urination or defecation.
Bradycardia
AS WE AGE There is a decrease in the speed of nerve
conduction.
Decrease in reflexes.
Less efficient sympathetic nervous system response may cause transient hypotension and fainting.
Decline in nerve activity supplying changes in pupillary response and reactivity.
Decrease in the cranial nerves mediating taste and smell.
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